A package insertion error protection structure has been known in which an insertion error protection hardware of U-shaped of which the front end at the left and right or any one side of the front plate installed as a hook shape at the front end of the package is directed towards the inside, and a key home fitting only with the insertion error protection hardware is installed at the front plate of the abutting package.
However, in the package insertion error protection structure described above, the package is to be pulled out in a specific order. For example, when a package is out of order and replaced, all the packages inserted after the broken package should be pulled out.
The following are reference documents.
[Document 1] Japanese Unexamined Utility Model Registration Application Publication No. H07-29889,
[Document 2] Japanese Unexamined Utility Model Registration Application Publication No. H03-41990, and
[Document 3] Japanese Unexamined Utility Model Registration Application Publication No. S62-201991.